If you’ve ever signed up for a charity ride, fondo, or other endurance event and wondered how you’d fit in all the training, you no doubt rejoiced upon learning about the benefits of high-intensity interval training. Big fitness! More speed! In half the time!

Whoa. Slow down. Because if you don’t keep your training mellow—at least some of the time—your progress will sputter to a halt. Therein lies the imperative for base training, the process of gradually developing a platform for your fitness.

“Base training is the foundation upon which everything else rests,” says Danny­ Suter, USA Cycling Level 2 coach and founder of the Boulder Performance ­Network. When you build endurance, eventually you can get more out of higher-­intensity riding and a heavier training load. “Riders who go straight into speed work can get fast on the bike,” says Hunter Allen, coauthor of Training and Racing with a Power Meter. “But they won’t have aerobic endurance, so their fitness lasts just a few weeks before they slow down.”

When you ride for two or more hours (or less for new riders) at a steady pace—a typical base ride—your body responds with changes that allow you to use more oxygen and burn more fat as fuel, says coach Joe Friel, author of The Cyclist’s Training Bible. For starters, these rides build more ­capillaries, the tiny blood vessels that deliver oxygen-rich blood to your muscles. Your mitochondria—the parts of your cells that produce energy—also multiply and enlarge. And you churn out more enzymes that help turn stored fuel into energy. The result: You can ride faster and longer.

Finally, and maybe more important, base-building rides tend to be the most social and fun, so you can just enjoy being on your bike, hanging out with friends, and recharging your batteries without worrying about going hard or being dropped. “Too many riders are in a hurry to get right to the high-intensity work,” says Friel. “They usually burn out by May.”

Strong base building starts with solid rest. “Everyone needs a break from hard efforts and structured riding so they can repair and recharge,” says Suter. Take a few weeks after a period of intense riding or your most recent goal event to rest, cross-train, and just catch up on life. “Back off enough to recover, but not so much that you completely lose fitness,” says Suter. Building a solid base also requires that you work on other key fundamentals, like general strength and technique, which are essential for long rides. Here are some guidelines.